Magnetic recording transducer

ABSTRACT

A magnetic recording transducer comprises a magnetoresistive sensor having a left side, a right side opposite to the left side, a left junction angle at the left side, a right junction angle at the right side, and a track width. The right junction angle and the left junction angle are characterized by a junction angle difference of not more than six degrees. The track width is less than one hundred nanometers. The magnetic recording transducer further comprises a left hard bias structure residing adjacent to the left side of the magnetoresistive sensor, and a right hard bias structure residing adjacent to the right side of the magnetoresistive sensor.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.12/560,669, filed on Sep. 16, 2009, now U.S. Pat. No. 8,233,248, whichis hereby incorporated by reference in its entirety.

BACKGROUND

FIG. 1 depicts a conventional method 10 for fabricating amagnetoresistive sensor in magnetic recording technology applications.FIGS. 2-3 depict a conventional transducer 50 during fabrication usingthe method 10. The method 10 typically commences after a conventionalmagnetoresistive, or MR, stack has been deposited. The conventionalmagnetoresistive stack typically includes an antiferromagnetic (AFM)layer, a pinned layer, a nonmagnetic spacer layer, and a free layer. Inaddition, seed and/or capping layers may be used. The pinned layer maybe a synthetic antiferromagnetic (SAF) layer including magneticallycoupled ferromagnetic layers separated by a nonmagnetic spacer layer.The nonmagnetic spacer layer may be a conductive layer for a giantmagnetoresistive sensor or an insulator for a tunneling magnetoresistivesensor. The free layer is ferromagnetic and has a magnetization that isfree to change in response to an external magnetic field, for examplefrom a media.

The conventional method 10 commences providing a conventional organicmask, via step 12. The conventional organic mask provided in step 12 istypically a photoresist mask. The conventional photoresist mask coversthe region from which the conventional magnetoresistive sensor is to beformed, as well as the field region of the transducer 50. However, partof the device region adjoining the magnetoresistive sensor is leftuncovered. The magnetoresistive sensor is defined, via step 14. Step 14typically includes ion milling the transducer 50. Thus, the portion ofthe magnetoresistive stack exposed by the conventional photoresist maskis removed. FIG. 2 depicts air-bearing surface (ABS) and plan views of aconventional, magnetic recording read transducer 50 after step 14 iscompleted. For clarity, FIG. 2 is not drawn to scale and only certainstructures are depicted. The conventional transducer 50 magnetoresistivelayers 54 which have been defined to provide a conventionalmagnetoresistive sensor 56. Because the regions adjacent to theconventional magnetoresistive sensor 56 were exposed, the conventionalmagnetoresistive sensor 56 has been formed. Also shown is conventionalphotoresist mask 58 which has a first portion 62 covering themagnetoresistive sensor 56 and remaining portions 60 that cover theremaining device and field regions. The photoresist mask 58 used istypically very thick. For example, the photoresist mask may be on theorder of one hundred sixty nanometers or higher.

The hard bias material(s) are deposited, via step 16. In addition, seedand/or capping layers may be provided in step 16. The hard biasmaterial(s) and other layers are deposited while the conventionalphotoresist mask 58 is in place. A lift-off of the conventionalphotoresist mask 58 is then performed, via step 18. FIG. 3 depicts theconventional transducer 50 after step 18 is performed. Thus, the hardbias material(s) 64 are shown. The hard bias material(s) to the left aredenoted 64L, while the hard bias material(s) to the right of themagnetoresistive sensor 56 are denoted 64R. Fabrication of theconventional transducer 50 may be completed.

Although the conventional method 10 allows the conventional transducer50 to be fabricated, there are several drawbacks. In particular, theremay be asymmetries in the conventional transducer 50. As can be seen inFIGS. 2-3, the conventional magnetoresistive sensor 56 is asymmetric.These asymmetries may become significant at smaller track widths, forexample thirty to forty nanometers or less. In particular, the junctionangles θ and φ may differ significantly. Further, multiple transducers50 are typically fabricated from a single wafer. There may also bevariations in the junction angles between transducers 50 fabricated onthe same wafer. Transducers closer to the center may have a smallervariation in junction angles than transducer 50 closer to the edge. Forconventional transducers 50, the average difference between the leftjunction angle φ and the right junction angle θ may be seven or moredegrees. Further, as can be seen in FIG. 3, the hard bias 64L and 64Rare asymmetric. Again, this asymmetry may vary across a wafer. Thesevariations between conventional transducers 50 may adversely affectperformance and/or yield.

Accordingly, what is needed is a system and method for improving thefabrication of a magnetic recording read transducer.

BRIEF SUMMARY OF THE INVENTION

A method and system for fabricating a magnetic transducer is described.The transducer has a device region, a field region, and amagnetoresistive stack. The method and system include providing a hardmask on the magnetoresistive stack. The hard mask is an inorganic maskand includes a sensor portion and a line frame. The sensor portioncovers a first portion of the magnetoresistive stack corresponding to amagnetoresistive structure. The line frame covers a second portion ofthe magnetoresistive stack in the device region. The method and systemalso include defining the magnetoresistive structure in a track widthdirection using the hard mask and providing at least one hard biasmaterial after the magnetoresistive structure is defined. A firstportion of the at least one hard bias material is substantially adjacentto the magnetoresistive structure in the track width direction. Themethod and system also include removing a second portion of the at leastone hard bias material. In one aspect, the magnetoresistive structure ischaracterized by a junction angle difference between junction angles onopposing sides of the magnetoresistive structure, In such an aspect, theaverage junction angle difference does not exceed six degrees. Inaddition, the track width in this aspect is less than or equal to onehundred nanometers.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a flow chart depicting a conventional method for fabricating amagnetic recording transducer.

FIG. 2 depicts plan and ABS views of a conventional magnetic recordingtransducer during fabrication.

FIG. 3 depicts plan and ABS views of a conventional magnetic recordingtransducer during fabrication.

FIG. 4 is a flow chart depicting an exemplary embodiment of a method forfabricating a magnetic recording transducer.

FIG. 5 depicts plan and ABS views of an exemplary embodiment of amagnetic recording transducer.

FIG. 6 is a flow chart depicting another exemplary embodiment of amethod for fabricating a magnetic recording transducer.

FIGS. 7-16 depict plan and ABS view of another exemplary embodiment of amagnetic recording transducer during fabrication.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 4 is an exemplary embodiment of a method 100 for providing magneticrecording transducer. For simplicity, some steps may be omitted. Themethod 100 is also described in the context of providing a singlerecording transducer. However, the method 100 may be used to fabricatemultiple transducers at substantially the same time. The method 100 isalso described in the context of particular layers. A particular layermay include multiple materials and/or multiple sub-layers. The method100 also may start after formation of other portions of the magneticrecording transducer. For example, the method 100 commences afterdeposition of magnetoresistive layer(s) for a magnetoresistive stack.The magnetoresistive layers may includes a pinning layer, a pinnedlayer, a nonmagnetic spacer layer, and a free layer. In addition, seedand/or capping layers may be used. The pinning layer may be an AFM orother layer configured to fix, or pin, the magnetization of the pinnedlayer. The pinned layer may be a synthetic antiferromagnetic (SAF) layerincluding magnetically coupled ferromagnetic layers separated by anonmagnetic layer. The ferromagnetic layers may be termed pinned andreference sub-layers. The nonmagnetic spacer layer may be a conductivelayer for a giant magnetoresistive structure, an insulator for atunneling magnetoresistive structure, or may have another structure. Thefree layer is ferromagnetic and has a magnetization that is free tochange in response to an external magnetic field, for example from amedia. The free layer may have multiple sub-layers, as may the pinnedand reference sub-layers. Further, the transducer may be considered tohave a device region, in which the magnetoresistive structure is to beformed, and a field region distal from the magnetoresistive structure.

A hard mask is provided on the magnetoresistive stack, via step 102. Thehard mask is inorganic and includes a structure portion and a lineframe. In some embodiments, for example in which the structure is amagnetoresistive sensor, the structure portion of the hard mask may alsobe termed a sensor portion. The structure portion of the hard maskcovers a part of the magnetoresistive stack corresponding to themagnetoresistive structure being formed. The line frame covers a secondportion of the magnetoresistive stack in the device region. In someembodiments, the line frame may be significantly wider than the sensorportion. For example, the line frame may have a width on the order of atleast two hundred nanometers, while the structure portion has a width onthe order of sixty nanometers or less. In some embodiments, the width ofthe sensor portion may be thirty to forty nanometers or less. Step 102may include depositing a hard mask layer, then patterning the hard masklayer to form the hard mask. The hard mask provided in step 102 shouldbe resistant to removal in the process used to define themagnetoresistive structure in step 104, described below. For example, insome embodiments, the hard mask includes one or more of diamond-likecarbon (DLC), SiC, and SiN. Further, the hard mask may be relativelythin. In one embodiment, the hard mask has a thickness of not more thanseventy nanometers. In one such embodiment, the hard mask has athickness of not more than sixty nanometers. In some embodiments, thehard mask is also configured to provide a magnetoresistive structurehaving a small width of not more than one hundred nanometers. In somesuch embodiments, the width may be smaller, for example not more thansixty nanometers. In some embodiments, the width may be thirty to fortynanometers or less.

The magnetoresistive structure is defined at least in a track widthdirection using the hard mask, via step 104. In one embodiment, step 104includes performing an ion mill to remove exposed portions of themagnetoresistive stack.

One or more hard bias materials are provided after the magnetoresistivestructure is defined, via step 106. Thus, a portion of the hard biasmaterial(s) is substantially adjacent to the magnetoresistive structurein the track width direction. If the magnetoresistive structure is to beused in a current-perpendicular-to-plane (CPP) configuration, then aninsulator might be provided prior to the hard bias material(s) in step106. In addition, seed and/or capping layers may also be provided instep 106. For example, the capping layer(s) may include a trilayerhaving Ru sub-layer sandwiched between Ta layers.

A portion of the hard bias material(s) is removed in step 108. Step 108includes removing the hard bias materials at least in the field regionof the magnetic recording transducer. In such an embodiment, the deviceregion of the transducer may be covered, for example by an organic mask.The hard bias material(s) in the exposed, field regions may then beremoved. In addition, step 108 may include removing any hard biasmaterial(s) residing on the magnetoresistive structure. Further,portions of the hard mask may also be removed, for example using areactive ion etch having the appropriate chemistry. Fabrication of thetransducer may then be completed.

FIG. 5 depicts plan and ABS views of an exemplary embodiment of amagnetic recording transducer 120 fabricated using the method 100. Forclarity, FIG. 5 is not drawn to scale. Further, although described inthe context of layers, structures in the magnetic recording transducer120 may include one or more sub-layers. For simplicity, only portions ofthe transducer 120 are shown. In some embodiments, the transducer 120may be part of a head. The head may be a merged head including at leastone write transducer (not shown) in addition to at least one readtransducer 120. Further, the head may reside on a slider (not shown) andbe part of a disk drive including the head, slider and media (not shown)on which data is written.

The transducer 120 includes a substrate 122 and magnetoresistive layers124 defined from a magnetoresistive stack. In addition, the transducer120 includes magnetoresistive structure 130 and hard bias structures140. The magnetoresistive structure 130 is a read sensor. The MR layers124 and read sensor 130 may be deposited as a full film. The read sensor130 is then defined using step 104. The hard bias 130 may be provided asa full film. However, because the hard mask and/or other structures maybe removed during fabrication, the hard bias 140 adjacent to themagnetoresistive structure 130 and magnetoresistive layers 124 remains.In the embodiment shown, the magnetoresistive sensor 130 is to be usedin a CPP configuration. Consequently, an insulating layer 142 is alsoprovided between the hard bias material(s) 140 and the magnetoresistivesensor 130.

The magnetoresistive sensor 130 has a track width, w. The track widthcorresponds to a characteristic distance between the right and leftsides. In some embodiments, the magnetoresistive sensor 130 has a trackwidth of not more than one hundred nanometers. In some embodiments, thetrack width may be smaller. For example, in one embodiment, the trackwidth, w, is not more than sixty nanometers. In other embodiments, w isnot more than thirty to forty nanometers.

The magnetoresistive sensor 130 had has a left side having a junctionangle α and a right side having a junction angle β. The junction anglesfor the magnetoresistive sensor 130 and others formed in a similarmanner may be characterized by an average junction angle difference. Theaverage junction angle difference is the average of the differencesbetween the junction angles α and β for a number of transducers 120. Theaverage junction angle difference being not more than six degrees. Insome embodiments, the average junction angle difference is not more thanfour degrees. In another embodiment, the average junction angledifference is not more than three degrees. In yet another embodiment,the average junction angle difference is not more than two degrees.

Using the method 100, the transducer 120 may be formed. As discussedabove, the transducer 120 is symmetric. Thus, the junction angles α andβ may be closer in size. In particular, it has been determined thatasymmetries in the portion 62 of the thick photoresist mask 58 shown inFIG. 2 may result in the asymmetries in the conventional sensor 56 andhard bias 64. More specifically, it has been determined that variationsin the junction angles may be due to the directional nature of the ionbeam used in defining the conventional sensor 56, the large height ofthe photoresist mask 58, and the asymmetric shape of the top of theportion 62 of the photoresist mask. In contrast, the hard mask providedin step 102 is thinner, and remains substantially unchanged andsubstantially symmetric. Thus, use of the hard mask in steps 102 and 104may improve the symmetry of the magnetoresistive sensor 130. Thejunction angles α and β may, therefore, be significantly more symmetric.In other words, the difference between the junction angles, as well asthe average junction angle difference across multiple transducers 120,may be reduced. Further, the thicknesses of the hard bias material(s)140 adjacent to the left and right sides of the sensor 130 may be moresymmetric. Consequently, asymmetries in the transducer 120 may bereduced. In addition, because a line frame is used, removal of a portionof the hard bias may be facilitated. Thus, performance of the transducer120 and yield using the method 100 may be improved.

FIG. 6 is a flow chart depicting another exemplary embodiment of amethod 150 for fabricating a magnetic recording transducer. FIGS. 7-16depict plan and ABS view of another exemplary embodiment of a magneticrecording transducer 200 during fabrication. The method 150 is describedin the context of the transducer 200. For simplicity, some steps of themethod 150 may be omitted. The method 150 is also described in thecontext of providing a single recording transducer 200. However, themethod 150 may be used to fabricate multiple transducers atsubstantially the same time. The method 150 and transducer 200 are alsodescribed in the context of particular layers. A particular layer mayinclude multiple materials and/or multiple sub-layers. The method 150also may start after formation of other portions of the magneticrecording transducer 200.

A magnetoresistive stack is deposited, via step 152. Themagnetoresistive layers may includes a pinning layer, a pinned layer, anonmagnetic spacer layer, and a free layer. In addition, seed and/orcapping layers may be used. Examples of such layers are described above.Further, the transducer may be considered to have a device region, inwhich the magnetoresistive structure is to be formed, and a field regiondistal from the magnetoresistive structure.

A hard mask layer is provided on the magnetoresistive stack, via step154. Step 154 includes blanket depositing an inorganic hard mask layer,such as DLC, SiN, and/or SiC on the magnetoresistive stack. In oneembodiment, step 154 includes depositing a hard mask layer having athickness of not more than seventy nanometers. In another embodiment,the hard mask layer provided in step 154 has a thickness of not morethan sixty nanometers.

A photoresist mask is provided, via step 156. The photoresist mask isused in patterning the hard mask layer to form the hard mask. Thus, thephotoresist mask covers a first portion of the hard mask layercorresponding to the sensor portion of the hard mask and a secondportion corresponding to the line frame of the hard mask. FIG. 7 depictsthe transducer 200 after step 156 is performed. Thus, a substrate 202and magnetoresistive stack 204 are shown. In addition, the hard masklayer 206 is shown as being blanket deposited on the magnetoresistivestack. Further, the photoresist mask 208 is also shown. The photoresistmask 208 has portions 208A and 208B corresponding to themagnetoresistive structure and the line frame, respectively. The portion208A corresponding to the magnetoresistive sensor may be printed with acritical dimension at the limit of the photo process used for thephotoresist mask 208. However, the width of the line frame may belarger, for example on the order of two hundred nanometers or more.

A portion of the hard mask layer is removed to form the hard mask, viastep 158. Thus, the pattern of the mask 208 is transferred to the hardmask layer 206. In one embodiment, step 158 is performed using areactive ion etch (RIE). FIG. 8 depicts the transducer 200 after step158 is performed. Thus, a hard mask 206′ has been formed. The hard mask206′ corresponds to the locations of portions of the mask 208. Theportion of the hard mask 206′ under the mask portion 208A corresponds tothe sensor in the device region. The portion of the hard mask 206′ underthe mask portion 208B corresponds to the line frame. Also in step 208,the photoresist 165 may be removed, for example via a photoresist strip.Thus, through steps 154-158, the hard mask 206′ is provided.

The magnetoresistive structure is defined in the track width direction,via step 160. In step 160, the hard mask 206′ is used to protectportions of the magnetoresistive stack 204 from the process. In oneembodiment, defining the magnetoresistive structure in a track widthdirection includes performing an ion mill. FIG. 9 depicts the transducer200 after step 160 is performed. Thus, a magnetoresistive structure 210has been defined. In one embodiment, the structure, magnetoresistivelayers 204A′ corresponding to the line frame of the hard mask have beendefined from the magnetoresistive stack 204. In addition,magnetoresistive layers 204′ in the field region have also been defined.The sensor 210 has a track width of not more than one hundrednanometers. In other embodiments, the track width may be smaller. Forexample, in one embodiment, the track width, w, is not more than sixtynanometers. In other embodiments, w is not more than thirty to fortynanometers. In contrast, the width of portions 204A′ may be larger asthese portions correspond to the line frame. In some embodiments, theportions 204A′ may be two hundred nanometers or more in width.

An insulator is optionally provided after the magnetoresistive structure210 is defined, via step 162. Step 162 is performed if the sensor 210 isto be used in a CPP configuration. At least one hard bias material afterthe insulator is provided, via step 164. A first portion of the hardbias material(s) is substantially adjacent to the magnetoresistivestructure in the track width direction. In some embodiments, cappinglayer(s) for the hard bias material(s) may also be provided in step 164.In some embodiments, the capping layer may have sub-layer(s). Forexample, providing a plurality of sub-layers may include providing afirst Ta sub-layer, a Ru sub-layer, and a second Ta sub-layer. In suchan embodiment, the Ru sub-layer resides between the Ta sub-layers. FIG.10 depicts the transducer 200 after step 164 is performed. Thus, hardbias layer 220 and capping layer(s) 222 are shown.

A portion of the hard bias material(s) 220 is removed, via step 166. Theportion removed resides on the hard mask 206′ above the sensor 210 andthe line frame 204A′, Step 166 may include performing a high angle ionmill, for example at an angle of sixty or more degrees from normal tothe surface of the transducer 200. FIG. 11 depicts the transducer 200after step 166 is performed. The portions of the hard bias material(s)220 and capping layer(s) 222 on the hard mask 206′ are shrunk. Thus, thehard bias 220′ and capping layers 222′ are shown. In some embodiments,the portion of the hard bias material(s) 220 above the magnetoresistivestructure 210 is completely removed. This situation is shown in FIG. 11.However, in other embodiments, some portion of the hard bias material(s)220 on the sensor 210 remain.

An organic device region mask is provided after the portion of the hardbias material(s) is removed, via step 168. Step 168 may include spinningon a layer of photoresist, then patterning the photoresist usingphotolithography. The organic device region mask covers at least thedevice region and leaves at least a portion of the field regionuncovered. An exposed portion of the hard bias material(s) is removedwhile the organic device region mask remains in place, via step 170.Thus, exposed hard bias in the field region may be removed. In oneembodiment, step 170 may be performed using an ion mill. FIG. 12 depictsthe transducer 200 after step 170 is performed. Thus, the device regionmask 230 is shown. The organic device region mask 230 covers most thedevice region of the transducer 200, but leaves the field regionexposed. In addition, the exposed portion of the hard bias material(s)220′ and capping material(s) 222′ in the field region have been removed.Thus, hard mask 206′ in the field region is exposed.

The device region mask is removed after the exposed portion of the hardbias material(s) 220′ have been removed, via step 172. Step 172 mayinclude stripping the photoresist mask 230. FIG. 13 depicts thetransducer 200 after step 172 is performed. Thus, the device region ofthe transducer 200 is exposed.

A chemical mechanical planarization (CMP) is performed to remove aportion of the material(s) residing on the hard mask, via step 174.Thus, portions of the hard bias material(s) 220′ that protrude from thetransducer 200 are removed. As a result, the hard mask 206′ is exposed,and may be removed. FIG. 14 depicts the transducer 200 after step 174 isperformed. Thus, the hard mask 206″ has been thinned and is exposed. Theprotruding portions of the hard bias 220′ have been removed. The hardbias material(s) 220″ and capping layer(s) 222″ remain.

The hard mask 206″ is removed, via step 176. In one embodiment, step 176includes performing a RIE to remove the hard mask 206″. For example, ifa DLC hard mask 206′ is used, step 176 may include performing an oxygenRIE. FIG. 15 depicts the transducer 200 after step 176 is performed.Thus, MR layers 204A′ that reside under the line portion of the hardmask 206′ are exposed.

A second CMP may be performed after the step of performing the RIE iscompleted, via step 178. Thus, the topology of the transducer 200 may befurther smoothed. FIG. 16 depicts the transducer 200 after step 178.Thus, hard bias structures 220′″ and capping layers 222′″ are shown.Thus, through step 174-178, the remaining hard mask has been removed.

Using the method 150, the transducer 200 may be formed. As discussedabove, the transducer 200 is symmetric. Thus, the junction angles α andβ may be closer is size. In particular, the average difference injunction angles α and β may be not more than six degrees. In someembodiments, average junction angle differences of four degrees or lessmay be fabricated. In other embodiments, average junction angledifferences of four degrees or less may be fabricated. In anotherembodiment, the average junction angle difference is not more than threedegrees. In yet another embodiment, the average junction angledifference is not more than two degrees. Further, asymmetries in thethicknesses of the hard bias structures 220′″ to the left and right ofthe magnetoresistive structure 210 may be reduced. Consequently,asymmetries in the transducer 200 may be reduced. This may be achievedfor a magnetoresistive structure 210 having a smaller track width. Forexample, the track width, w, is less than one hundred nanometers. Insome embodiments, the track width may be thirty to forty nanometers orless. In addition, because a line frame is used, removal of the hardbias 220′ may be facilitated. Thus, performance of the transducer 200and yield using the method 150 may be improved.

We claim:
 1. A magnetic recording transducer comprising: amagnetoresistive sensor having an left side, a right side opposite tothe left side, a left junction angle at the left side, a right junctionangle at the right side, and a track width, the right junction angle andthe left junction angle being characterized by a junction angledifference, the junction angle difference being not more than sixdegrees, the track width being less than one hundred nanometers; a lefthard bias structure residing adjacent to the left side of themagnetoresistive sensor; and a right hard bias structure residingadjacent to the right side of the magnetoresistive sensor.
 2. Themagnetic recording transducer of claim 1 wherein the junction angledifference is not more than four degrees.
 3. The magnetic recordingtransducer of claim 1 wherein the junction angle difference is not morethan three degrees.
 4. The magnetic recording transducer of claim 1wherein the junction angle difference is not more than two degrees.
 5. Adisk drive comprising: a slider; a magnetic recording head coupled tothe slider, the magnetic recording head including a magnetic recordingtransducer having a magnetoresistive sensor, the magnetoresistive sensorhaving a left side, a right side opposite to the left side, a leftjunction angle at the left side, a right junction angle at the rightside, and a track width, the left junction angle and the right junctionangle being characterized by a junction angle difference, the junctionangle difference being not more than six degrees, the track width beingless than one hundred nanometers.
 6. The disk drive of claim 5 whereinthe junction angle difference is not more than four degrees.
 7. The diskdrive of claim 5 wherein the junction angle difference is not more thanthree degrees.
 8. The disk drive of claim 5 wherein the junction angledifference is not more than two degrees.